my bro says priest but i say druid hlp me NOW PLEASE! I BEG OF U!

Hmm depends what u are looking for ... if its like pvp it should be a paladin ... but for somthing like pve druid can be very good and a priest .. but all in all i think priests are very good.

Priests man, at lvl 1 they heal 45-60 or somthing

I have a level 70 resto druid and a level 70 dsc/holy priest.  The druid is raiding Hyjal and the Priest just started SSC. (Meaning the druid is slightly better geared than the priest.) Both have healed through Zul'Aman.  So perhaps I can give one PvE raider's perspective on healing with these two classes.

Resto (Tree of Life) Druid: 

Strengths:

Moving fights --  There are fights when standing still is a liability or when the raid is so spread out that the ability to 'chase' people in need of healing is a huge asset.  This is a job for your druid.

Fast (instant) heals -- I can instantly nature's swiftness a healing touch on someone for 7.5-10.5k(crit) health every 3 min... and can swiftmend a rejuv on someone for 6.5-7.5 health every 15 seconds.  This is in addition to having HoT's ticking and casting Healing Touch.

Big, Bad, Long HoTs -- Rejuvenation will tick for 12 seconds at 1100 to 1500 per tick.  Regrowth hits the target for around 4.2k and ticks for 21 seconds at about 400ish per tick.  Lifebloom ticks 5 times at around 320 (per stack) and then 'blooms' onto the target for 2400-3400.  Even better, the 'bloom' aggro counts as if the target healed himself!

Mana efficiency -- My druid solo-healed Prince once for 14 min when we lost the other healer and three dpsers during the first infernal drop.  The resulting decrease in raid dps made it a LONG fight and it took every trick in my arsenal (and his, and our off-tank's) to keep our tank up.  But I know there is no way my priest's mana would have survived that kind of pounding.  Druidic heals simply cost less per hph, and innervate beats shadow fiend hands down for mana return.

Anticipatory healing -- The large selection of HoT's means that that I can heal ahead of need, lowering the risk of burst damage amounting to more than I can overcome.  It also makes things like tossing a rejuv + Lifebloom on a life-tapping warlock absolutely no big deal. 

Battle Rez -- this is a wipe saver over and over and over.  I truly perfer it to the ability to rez everyone OOC since by then the battle is usually lost.  I don't like losing.

Poison/Curse removal -- There are a lot of fights were this is necessary, and I miss it horribly on my priest.

Mark of the Wild -- Resistances/stats/armor... what a lovely buff, especially to your tank, who has good melee mitigation, but not magical resistance.

Cons

Speed -- ToL form gives a 20% speed debuff, which is a liability in some fights, so that I stay in caster 90% of the time anymore unless I know the fight is going to be long, am pretty sure I'm not going to need to use Healing Touch or remove curses, and am pretty sure that speed isn't going to be necessary.  Popping in and out of ToL form even once negates the mana bonus in any fight lasting less than 5 minutes. 

Lack of good group heals --  Tranquility is awesome - mine ticks for nearly 3k on everyone in my party so that even a tank or warlock will be fully restored (minus damage taken).  It is also threat free.  But with a 10 min CD it is truly an 'oh shit' heal.  If it were on a 5 min CD or hit everyone in a raid it would be SO much more useful.  As it is, I rarely have cause to use it anymore since I rarely need it in 5 mans and am not usually placed with the tank group in raids. 

No aggro dump -- Druidic healers have NO way to drop aggro in a hurry if they manage to overtake the tank.  In fights with aggro resets this is a horrible liability.  For instance in Heroic Ramps when the dragon 'descends from the sky' he fireballs my healer every time (I stay bubbled for that fight and fade as soon as the message appears on my priest).  A good percentage of the time it is fatal for my druid.  Nightbane is the same way during this transition.  The only counter to this seems to be to have a hunter with MD at the ready.  Blizzard could easily give druids an 'out' for this by having cat-form 'cower' be energy free, but by time I switch to cat and wait for the energy to build to 'cower' I'm either dead or someone else is.  Enchanting her cloak for subtely and maxing the talent by the same name helps, but is not nearly as effective as a priest's fade.

No wand -- in a fight where I need to conserve my mana for healing, I have no real way to join in the fun and stay out of melee range (there are an awful lot of fights with melee-range environmental or AoE damage).  I fairie fire mobs for what little help that is to the team (just as I SW:P mobs as a priest), but I do miss having a wand...

No group abolish poison/curse:  I can understand not giving druids the ability to cleanse magic, but I really think they need a mass abolish poison.


Priest

Benefits

Selection of heals:  I have Renew - Flash Heal - Heal - Greater Heal - Prayer of Healing - Prayer of Mending all on my heal bar.  That's a lot of choices to maximize healing while using as little mana as possible.

More +Heal:  My druid is in 100% leather other than her cloak, and fully gemmed/enchanted for +heal still has -100 less +heal than my priest, who is partially gemmed/enchanted for stam/spirit/Mp5.  That in combination with the fact that priest heals are designed to be bigger mean that my priest can nuke heal like a mad-woman. 

Group heals: I opted out of CoH in favor for IDS, so I won't comment on that.  But I use Prayer of Healing/Mending all the time.  Prayer of Healing is insanely mana efficient if the group is taking environmental damage.  And PoM is terrific for pre-emptory healing and spot healing non-party members. 

Mass dispel:  Enough said.

Fear ward/fear:  I soloed a lot of group quests on level by dotting and fearing and kiting and bubbling.  The ability to keep the tank from being feared is priceless.  The ability to fear boss adds is priceless as well if there is no warlock in the group.

Terrific buffs:  I went far enough down the discipline tree to get IDS - which gives +50 spirit and +10% of target's spirit to bonus spell damage/healing.  And of course, imp fort gives the group ~1k more hit points.  Pretty nice no matter what class you are.  Shadow protection means your pallies can use a different aura.  When inspiration procs on your tank during heavy melee fights it is astoundingly easy to keep him up with less spam healing.

Dispel Magic:  You can make a lot of mobs a LOT squishier by removing their buffs - not to mention removing debuffs on party members and the pvp applications..

Aggro dump:  Fade, fade, fade, fade, fade.... I love my fade button for trash pulls. The aggro just comes right back, but by then the mob us almost always engaged elsewhere. 

PW:S:  This is a terrific tool for both protecting yourself and buying a bit of time to save someone else.  As it is mana-inefficient you don't want to abuse it, but it is one of the things I most wish my druid had.  Some will say that 'druids don't need a bubble, they wear leather' but leather doesn't protect against magical damage, nor can I pop my leather on someone else.  And with innner fire, the difference in armor between my priest and druid is negilible.

Offensive ability:  Having a wand means I can join in the fight while watching the health bars.  My priest is also a Nelf, so she has a mana-free DoT to add to the fight.  Wands are also much much better for stats than druidic idols, which only add a small buff to one ability. 

Disadvantages:

Slow:  Priests need TIME to heal, and often time is more precious than mana.  This is especially true in moving fights.  I would rather go to the dentist than heal the first boss fight in Heroic Auchenai Crypts on my priest...  What is an easy fight with my druid is just hard when you need 1.5-2.5 seconds to cast.

Poison:  I miss abolish poison on my priest more than I miss dispel magic on my druid.  Poisons like viper sting can be so nasty.   

No good 'oh shit' heal:  Though druidic tranquility is on a 10 min CD, it is so amazing in those times when you do need it, that not having something similar is painful. 

Only OOC rezzs:  Lazy people prefer not having to walk back if they die, but priests have no ability to save a group if a key member dies - and that is such a helpless feeling at times.  I also hate that some people expect me to walk back alone and rez the party - asking a cloth-wearing healer to do so seems insanely wrong to me, and I have been known to refuse to do so unless I was the direct cause of the wipe.  (We all pull a Leroy Jenkins now and then...)If we are all dead, we can all walk back.  Why should they get a bio break, but not me?

Lack of mana efficiency:  I have to manage my mana a great deal more on my priest and take a lot more mana pots.  It is very easy to cast a mana-bar away without even half trying.  My priest regens mana at -50 per tick than my druid as well, which does not help.  On the other hand her heals are bigger (by design and because of her higher +heal)... I think the theory is that you would not cast as many as a priest - totally true since I tend to chain-cast instants on my druid.  My priest DOES crit more - about 5% more, which may improve the hpm more than I think.

Sucky HoT:  In comparison to rejuv and lifebloom, renew sucks.  It doesn't tick as high or as long and there is no way to instantly dump the full heal on someone on the fly.  I suppose I should be glad to have a HoT at all.  It is at least less expensive than rejuv.


---

I would also add that aesthetically, the druids are a bit wild looking, with a lot of feathery gear.  Priests tend to look very girly.  Though I suppose there is no reason not to put your druid in cloth healing gear (other than the little bit of survivability from the armor). 

As to preference - If we were to run a five man twice with the same five people, once with my druid and once with my priest healing, both would heal equally well, but I would likely have more dps AND more overhealing on my druid (in spite of not having a wand... I tend to wrath spam between heals).  If we were in a pinch and needed one of my girls to duo-heal a kara group partnered with an undergeared or inexperienced healer, I'd take my druid.  Her heals aren't as big, but they are faster, making my reaction time easier (unless my heal-partner was a druid.  Need someone to dispel... and a shackle is nice) and I get more hpm.  If, however, my healing partner was going to be a decently geared non-priest (it is good to have variety and we need someone (a mage works) to remove curses), I'd take my priest. If I were asked to respec one of them to a dps class it would be my druid, though that has as much to do with the fact that I have a full t4/t5 equivalent boomkin set from our slow progress through Kara, Gruuls, Mag, TK, ZA, and SSC, than it is any preference in their healing style or boomkin versus spriest.  My priest is 'younger' and hasn't done nearly as much raiding.

That's all long and rambly, but perhaps it will give those of you some food for thought if you are debating which class of healer to roll. :)

Pal: more def and therefor dont die that easy

Priest: Singel massive healings and great buffs

Shaman: 3 healing spells tha covers Fast, Massive and grupe + totems help a lot

Druids: Simply Best: they heal the most, have good regn spells that are good for keeping dps and so alive + a massive healing that are gonna mae ur tank love u + instand cast regn, healing spell

Not disputing that a druid may be the most effective healer, but not all of what you wrote is completely accurate.

Paladin: Yes when it comes to defensive, no other healer can compare.  (assuming that the druid is actually healing and not in bear form)

Priest:  Have the most potent, "all at once" healing spells.  Priests have buffs, but they don't come close to the benefits of a paladin or especially a shaman.

Shaman: Good backup healers in my opinion.  The shaman has a lot of other crap they got to worry about.  Their buffs and totems make them very important in a group.

Druid:  Great HoT and quick heals.  Plus, they always have the benefit to turn into a bear if things go crazy.

If your group wipes a ton shaman:
-self rez
-rez everyone else

shamans self rez also

Ugg shammys heals suck, i remeber doing heroic UB and shammy could not keep 70 all epiced out durid and we wiped on the first mob for 4 deaths, and durids heals on tree form take a while to cast and are offen heals over time, i say priest due to the fact they can rez all the times and they are mainly healers,expect for shadow priest

long cooldown, so dont depend on it